Hydrogen Peroxide Gas Plasma Sterilization Research Articles

Effect of a hydrogen peroxide gas-plasma sterilization on physical integrity and quality of N95 respirators: An experimental study during the COVID-19 pandemic

Background: N95 respirators have prevented transmission among health-care workers during the COVID-19 pandemic. During times of intense shortage of respirators and border closures during the pandemic, re-use strategies with available decontamination methods were necessitated. This in-house experimental study evaluated the effect of hydrogen peroxide gas-plasma sterilization on respirators and helped establish an evidence-based protocol for their re-use in a resource-poor setting. Materials and Methods: A three-dimensional experimental model using saline nebulization as the aerosol exposure and a particle counter to measure the filtration of particles through the mask pre- and post-sterilization was used. Multiple cycles of plasma sterilization were done till the physical integrity/fit was lost. Total filtration volume was used as a surrogate marker to assess the filtration efficiency (FE). Results: The total volume of particles filtered on a 3M respirator was 99.9%. Unused Halyard and Venus respirators were compared against 3M and found to have FE of 99.9% and 60.5%, respectively. After repeated sterilization cycles, the total volume of particles filtered was 59.3% for Halyard in the seventh cycle and 36.2% for Venus in the fifth cycle. When the physical integrity and fit was tested, the appropriate fit was lost after eight cycles of sterilization for Venus and was not lost for Halyard even after the tenth cycle. Conclusion: This low-cost experimental study helped implement an effective and safe decontamination strategy for safe re-use of N95 respirators in an emergent situation with no access to commercial testing in a resource poor health-care setting during the pandemic.

The Effect of Disinfectants Absorption and Medical Decontamination on the Mechanical Performance of 3D-Printed ABS Parts.

Producing parts by 3D printing based on the material extrusion process determines the formation of air gaps within layers even at full infill density, while external pores can appear between adjacent layers making prints permeable. For the 3D-printed medical devices, this open porosity leads to the infiltration of disinfectant solutions and body fluids, which might pose safety issues. In this context, this research purpose is threefold. It investigates which 3D printing parameter settings are able to block or reduce permeation, and it experimentally analyzes if the disinfectants and the medical decontamination procedure degrade the mechanical properties of 3D-printed parts. Then, it studies acetone surface treatment as a solution to avoid disinfectants infiltration. The absorption tests results indicate the necessity of applying post-processing operations for the reusable 3D-printed medical devices as no manufacturing settings can ensure enough protection against fluid intake. However, some parameter settings were proven to enhance the sealing, in this sense the layer thickness being the most important factor. The experimental outcomes also show a decrease in the mechanical performance of 3D-printed ABS (acrylonitrile butadiene styrene) instruments treated by acetone cold vapors and then medical decontaminated (disinfected, cleaned, and sterilized by hydrogen peroxide gas plasma sterilization) in comparison to the control prints. These results should be acknowledged when designing and 3D printing medical instruments.

Can sterilization methods influence surface properties of resin composites? A purpose for previewing bias in laboratory bacterial adhesion tests.

This study aimed to evaluate the influence of sterilization methods on conventional and bulk-fill resin composites' (BFRCs) surface properties in an attempt to preview bias in laboratory bacterial adhesion tests. Two regular viscosity conventional resin composites [Filtek Z350 XT™ (Z350) and IPS Empress Direct™ (ED)] and two regular viscosity BFRCs [Filtek Bulk Fill™ (FILT) and Tetric N-Ceram Bulk Fill IVA™ (TBF)] were used. The materials were characterized by Scanning Electron Microscopy (SEM), surface roughness (SR), and wettability (W) after sterilization with hydrogen peroxide gas plasma (HPGP) and steam sterilization (SS). Nonsterilized samples served as a control group (n=5). Statistical analysis was performed using two-way analysis of variance (ANOVA) and Tukey post hoc test (p < 0.05). For SR, there were no statistically significant differences among the groups (p > .05). SS method decreased the contact angle for FILT and Z350 (p < .01). The SS promoted more exposition of filler particles, while the HPGP method did not alter the tested materials' morphology. Therefore, sterilization methods affected the resin composites tested selectively. HPGP seems to be the most recommended method to sterilize the tested resin composites before laboratory bacterial adhesion tests.

Geometric accuracy of an acrylonitrile butadiene styrene canine tibia model fabricated using fused deposition modelling and the effects of hydrogen peroxide gas plasma sterilisation

BackgroundThree-dimensional (3D) printing techniques have been used to produce anatomical models and surgical guiding instruments in orthopaedic surgery. The geometric accuracy of the 3D printed replica may affect surgical planning. This study assessed the geometric accuracy of an acrylonitrile butadiene styrene (ABS) canine tibia model printed using fused deposition modelling (FDM) and evaluated its morphological change after hydrogen peroxide (H2O2) gas plasma sterilisation. The tibias of six canine cadavers underwent computed tomography for 3D reconstruction. Tibia models were fabricated from ABS on a 3D printer through FDM. Reverse-engineering technology was used to compare morphological errors (root mean square; RMS) between the 3D-FDM models and virtual models segmented from original tibia images (3D-CT) and between the models sterilised with H2O2 gas plasma (3D-GAS) and 3D-FDM models on tibia surface and in cross-sections at: 5, 15, 25, 50, 75, 85, and 95% of the tibia length.ResultsThe RMS mean ± standard deviation and average positive and negative deviation values for all specimens in EFDM-CT (3D-FDM vs. 3D-CT) were significantly higher than those in EGAS-FDM (3D-GAS vs. 3D-FDM; P < 0.0001). Mean RMS values for EFDM-CT at 5% bone length (proximal tibia) were significantly higher than those at the other six cross-sections (P < 0.0001). Mean RMS differences for EGAS-FDM at all seven cross-sections were nonsignificant.ConclusionsThe tibia models fabricated on an FDM printer had high geometric accuracy with a low RMS value. The surface deviation in EFDM-CT indicated that larger errors occurred during manufacturing than during sterilisation. Therefore, the model may be used for surgical rehearsal and further clinically relevant applications in bone surgery.Graphical abstract

Evaluation of in Vitro Cytotoxicity Tests for Medical Material Using Hydrogen Peroxide Gas Plasma Sterilization

This paper aims to discuss the evaluation of in vitro cytotoxicity tests for eleven different medical materials using hydrogen peroxide gas plasma sterilization. Compared with ethylene oxide sterilization, the results show that only nylon material is not suitable for using hydrogen peroxide gas plasma sterilization.

Adverse Events with Low Temperature Hydrogen Peroxide Gas Plasma Sterilisation Reported by Certified Sterilisation Service Technicians and Certified Sterilisation Specialists in Japan

Adverse Events with Low Temperature Hydrogen Peroxide Gas Plasma Sterilisation Reported by Certified Sterilisation Service Technicians and Certified Sterilisation Specialists in Japan

Effects of sterilization with hydrogen peroxide gas plasma, ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints

To compare effects of sterilization with hydrogen peroxide gas plasma (HPGP), ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints. Samples of a 36.3-kg test nylon leader line, 57.8-kg test nylon fishing line, and 2-mm ultrahigh-molecular weight polyethylene (UHMWPE) were used. In this in vitro study, samples of nylon leader line, fishing line, and UHMWPE sterilized by use of HPGP, ethylene oxide, and steam or unsterilized samples were used. Bacterial adherence on unsterilized and sterilized samples was tested with Staphylococcus epidermidis and Escherichia coli. Five samples were examined for each line type and sterilization condition, and final colony counts were obtained. Bacterial adherence was significantly affected by method of sterilization for all 3 line types. For most of the samples, bacterial adherence was similar or lower when HPGP sterilization was used, compared with results for sterilization via ethylene oxide and steam, respectively. Bacterial adherence was significantly higher for UHMWPE, compared with adherence for the nylon line, regardless of the sterilization method used. Bacterial adherence was higher for nylon fishing line than for nylon leader line for S epidermidis after ethylene oxide sterilization and for E coli after HPGP and ethylene oxide sterilization. Effects of HPGP sterilization on bioadhesive properties of nylon and polyethylene lines compared favorably with those for ethylene oxide and steam sterilization. Also, nylon line may be a more suitable material than UHMWPE for suture prostheses on the basis of bacterial adherence properties.

Effects of Low-Temperature Hydrogen Peroxide Gas Plasma Sterilization on In Vitro Cytotoxicity of Poly(ϵ-Caprolactone) (PCL)

Our objective was to determine whether low-temperature hydrogen peroxide (H2O2) gas plasma sterilization of porous three-dimensional poly(ϵ-caprolactone) (PCL) constructs significantly inhibits cellular metabolism of canine chondrocytes. Porous cylindrical constructs were fabricated using fused deposition modeling and divided into four sterilization groups. Two groups were sterilized with low-temperature H2O2 gas plasma (LTGP) and constructs from one of those groups were subsequently rinsed with Dulbecco’s Modified Essential Media (LTGPDM). Constructs in the other two groups were disinfected with either 70% isopropyl alcohol or exposure to UV light. Canine chondrocytes were seeded in 6-well tissue-culture plates and allowed to adhere prior to addition of PCL. Cellular metabolism was assessed by adding resazurin to the tissue-culture wells and assessing conversion of this substrate by viable cells to the fluorescent die resorufin. This process was performed at three times prior to addition of PCL and at four times after addition of PCL to the tissue-culture wells. Metabolism was not significantly different among the different tissue-culture wells at any of the 3 times prior to addition of PCL. Metabolism was significantly different among the treatment groups at 3 of 4 times after addition of PCL to the tissue culture wells. Metabolism was significantly lower with constructs sterilized by LTGP than all other treatment groups at all 3 of these times. We conclude that LTGP sterilization of PCL constructs resulted in significant cytotoxicity to canine chondrocytes when compared to PCL constructs disinfected with either UV light exposure or 70% isopropyl alcohol.

Mechanical Evaluation of Hydrogen Peroxide Gas Plasma Sterilization of Nylon Lines Used for Extra-Articular Stabilization of the Canine Stifle Joint

To compare the effects of hydrogen peroxide gas plasma (HPGP) and ethylene oxide (EO) sterilizations on the mechanical properties of nylon lines used for stabilization of the canine stifle. Secondarily, to compare the performance of crimped and knotted lines. In vitro mechanical evaluation. Nonsterilized, EO- and HPGP-sterilized specimens of 36.3 kg test nylon leader line (NLL) and 57.8 kg test nylon fishing line (NFL). Single strands and looped specimens of NLL or NFL were positioned on a material testing machine. To create looped specimens, NLL were crimped using the Securos system, and NFL were knotted, as used clinically. Elongation (%) and ultimate load (N) variables were studied. Elongation and ultimate load of NLL groups were not significantly different between EO and HPGP. For NFL, HPGP sterilization led to slightly greater elongation than EO in loops only. Ultimate load of NFL single strands was not significantly different between EO and HPGP, but was higher after HPGP compared with EO in NFL loops. All NLL groups had less elongation and ultimate load than NFL. The effects of HPGP on NLL compared positively to EO, making HPGP an attractive alternative. As HPGP led to a slightly greater elongation of NFL than EO, the latter could be favored to sterilize NFL. Crimped NLL minimized elongation better than knotted NFL. Sterilization with HPGP seems a good alternative to EO for NLL. EO may be a better choice for NFL; however, it is difficult to judge the clinical relevance of this result. Crimped NLL minimizes elongation and may help reducing the recurrence of stifle instability postoperatively.

Inactivation of Animal and Human Prions by Hydrogen Peroxide Gas Plasma Sterilization

Prions cause various transmissible spongiform encephalopathies. They are highly resistant to the chemical and physical decontamination and sterilization procedures routinely used in healthcare facilities. The decontamination procedures recommended for the inactivation of prions are often incompatible with the materials used in medical devices. In this study, we evaluated the use of low-temperature hydrogen peroxide gas plasma sterilization systems and other instrument-processing procedures for inactivating human and animal prions. We provide new data concerning the efficacy of hydrogen peroxide against prions from in vitro or in vivo tests, focusing on the following: the efficiency of hydrogen peroxide sterilization and possible interactions with enzymatic or alkaline detergents, differences in the efficiency of this treatment against different prion strains, and the influence of contaminating lipids. We found that gaseous hydrogen peroxide decreased the infectivity of prions and/or the level of the protease-resistant form of the prion protein on different surface materials. However, the efficiency of this treatment depended strongly on the concentration of hydrogen peroxide and the delivery system used in medical devices, because these effects were more pronounced for the new generation of Sterrad technology. The Sterrad NX sterilizer is 100% efficient (0% transmission and no protease-resistant form of the prion protein signal detected on the surface of the material for the mouse-adapted bovine spongiform encephalopathy 6PB1 strain and a variant Creutzfeldt-Jakob disease strain). Thus, gaseous or vaporized hydrogen peroxide efficiently inactivates prions on the surfaces of medical devices.

Sterilization effects on starPEG coated polymer surfaces: characterization and cell viability

Sterilization is frequently an issue for polymeric biomaterials including hydrogels, where autoclaving needs to be discarded, and gamma-irradiation and low temperature hydrogen peroxide gas plasma sterilization are already important alternatives. Coatings based on poly(ethylene glycol) are a well-known strategy to reduce unspecific protein interactions on biomaterial surfaces. Dense, ultrathin coatings of isocyanate terminated star-shaped poly(ethylene glycol) (starPEG) molecules have proven to be resistant to unspecific adsorption of proteins and enable direct biofunctionalization. The effectivity and stability of the starPEG coatings on poly(vinylidene fluoride) (PVDF) were studied after gamma-irradiation (normed dosis 25 kGy) and plasma sterilization (Sterrad 100S). The selected surface properties determined were: surface composition (X-ray photoelectron spectroscopy, XPS), wettability (sessile drop contact angle) and protein adsorption by fluorescence microscopy (Avidin-TexasRed, Bovine Serum Albumin-Rhodamin). Preliminary cell experiments with the cell line L929 were performed prior and after sterilization to investigate the cell repellence of the starPEG coatings as well as cell viability and specific cell adhesion on GRGDS-modified coatings. The starPEG coating undergoes a slight oxidation due to plasma and gamma-sterilization; this represents a minor variation confirmed by XPS and contact angle results. The non-sterilized starPEG and the plasma-sterilized coatings are protein repellent, however the protein adsorption on starPEG coated substrates is much stronger after gamma-sterilization for both avidin and bovine serum albumin. The cell experiments indicate that the starPEG coatings are appliable homogeneously by incubation and are non-cell adherent. Moreover, after both sterilization processes the starPEG coatings remain cell repellent and the GRGDS-modified coatings presented vital cells. Thus we conclude that the plasma sterilization is more convenient for the starPEG coatings and GRGDS-modified starPEG coatings.

欧州における滅菌の最新事情と新型過酸化水素低温プラズマ滅菌装置の位置付け(第82回日本医科器械学会大会ランチョンセミナー5記録)

欧州における滅菌の最新事情と新型過酸化水素低温プラズマ滅菌装置の位置付け(第82回日本医科器械学会大会ランチョンセミナー5記録)

Application of Hydrogen Peroxide Gas Plasma Method for Porous Polyurethane Sterilization

Tissue-engineering must be either manufactured aseptically or sterilized after processing. To extend protection of medical devices against microbial contamination, various sterilization methods have been suggested. Hydrogen peroxide gas plasma sterilization has been applied in hospitals worldwide for almost a decade. In this study, we investigated the sterilization efficacy of hydrogen peroxide gas plasma sterilizer with porous polyurethane sample. The result is suggested that hydrogen peroxide gas plasma can be applicable to the sterilization of polymer scaffold for tissue engineering materials.

Sterility and Microbiological Assessment of Reused Single-Use Cardiac Electrophysiology Catheters

To assess the performance and limitations of a reprocessing protocol for nonlumen electrophysiology catheters by testing the sterility of reprocessed devices and defining the maximum number of reprocessing cycles sustainable by the device in hygienically safe conditions. Simulated use, reprocessing, and testing of the catheters. Microbiology and virology department of a public health diagnostic laboratory. Seventy-three catheters were collected after clinical use on patients. The first group of devices was tested for sterility after 1 cycle of reprocessing. By the repetition of simulated use (blood inoculated with bacteria) and reprocessing (decontamination, cleaning, and hydrogen peroxide gas plasma sterilization), we obtained 39 sample devices reprocessed 2 times, 26 reprocessed 3 times, 28 reprocessed 4 times, 36 reprocessed 5 times, and 22 reprocessed 6 times. Devices were cultured for 28 days in trypticase soy broth. We tested 208 catheters with 6 cycles of reprocessing and 4 inoculated bacteria species. No devices tested positive for the inoculated strains until the fourth cycle of reprocessing. One of 35 catheters showed the growth of the inoculated strain Bacillus subtilis after 5 cycles of reprocessing, and 1 of 22 catheters showed growth of this organism 6 cycles. After the second reprocessing, 7 of 36 devices showed growth of gram-negative bacteria other than the strain inoculated. Reprocessing according to the reprocessing protocol was insufficient to guarantee device sterility after 5 reuses. Cleaning with enzymatic solution revealed good cleaning properties with efficient bioburden reduction. Storage intervals of longer than 24 hours during reprocessing should be avoided to limit contamination or bacterial overgrowth. Technical considerations suggest the introduction of reprocessing procedures only in hospitals with considerable workloads.

La sterilità dei dispositivi monouso rigenerati. Studio su cateteri per cardiologia interventistica dopo riutilizzo simulato

The reuse of single use devices is of particular interest in interventional cardiology where the economic load of the devices represents a significant share of the whole procedure. The sterility of the reprocessed device must be tested and warranted, together with chemical-physical and functional performances. This study evaluates the efficiency and limitations of an experimental reprocessing protocol in order to assess the sterility of cardiac electrophysiology catheters and the maximum number of regeneration cycles sustainable by the device. A first lot of 54 devices, collected after clinical use in the Cardiology Department of S.Chiara Hospital in Trento, was reprocessed and tested for sterility. Devices underwent repeated cycles of simulating-use (bacteria spiked blood) and regeneration (decontamination, cleaning and hydrogen peroxide gas plasma sterilization): 36, 24, 28, 35, 22 devices were regenerated respectively 2, 3, 4, 5 and 6 times. Entire devices were cultured for 28 days in trypticase soy broth. On the whole,we tested 199 samples, six cycles of regeneration and four inoculation species. No positive sample to inoculated strain was found until the fourth cycle of reprocessing. The inoculated Bacillus subtilis strain was recovered in samples reprocessed five and six times. Reprocessing procedures following the adopted protocol turned out efficient to guarantee device’s sterility up to five reuses in experimental conditions representing the worst case scenario for bacterial load. However, complexity of reprocessing protocols, organizational issues, economic and legal requirements addressed to qualifying and certifying all steps of the reprocessing procedure discourage “in house” reprocessing.

Efficiency in endotoxin removal by a reprocessing protocol for electrophysiology catheters based on hydrogen peroxide plasma sterilization

Electrophysiology and ablation cardiac catheters, which come in contact with blood during clinical use, are required to be non-pyrogenic (<20 endotoxin units (EU)/device). This study aimed to quantify the residual endotoxin load in reprocessed devices as a mandatory step to guarantee safe reuse. We monitored the pyrogenic status of the device ( n=61) in three fundamental steps of the reprocessing protocol: after clinical use, after decontamination-cleaning treatments and after complete reprocessing, including sterilization by hydrogen peroxide gas plasma. Finally, a depyrogenation test was produced for evaluating the depyrogenation efficiency of the sole hydrogen peroxide sterilization treatment. Results showed that standard clinical use did not represent a source for endotoxin contamination, while the use of tap water and manual cleaning processing could increase the pyrogenic load in a significant way. The introduction of the sterilization by hydrogen peroxide gas plasma resulted in effective reduction of the endotoxin contamination and in safe reprocessing of 15 of 15 clinically used catheters. In addition, tests conducted on in vitro spiked catheters showed that initial pyrogenic loads of 40, 80, 200 EU/device were reduced to less than 11 EU/device. Depyrogenation testing demonstrated efficiency in endotoxin reduction of more than 62 times (1.8 log). These results show the determining role of hydrogen peroxide gas-plasma sterilization in the reduction of pyrogenic load on medical devices. Considering actual hygienic requirements at single-use device reprocessing, hydrogen peroxide gas-plasma sterilization can be considered as an efficient treatment at non-lumen cardiac electrophysiology catheter reprocessing.

Effect of sterilization on the physicochemical properties of molded poly(L‐lactic acid)

In this study, the process of manufacturing and sterilizing an orthopedic implant constructed from poly(L-lactic acid) (PLLA) was closely simulated. The hydrogen peroxide gas plasma (HPGP) sterilization process was comparatively investigated against ethylene oxide (EtO). Characterization of the physical, thermal, mechanical, morphological, and chemical properties was monitored. The results indicate that the HPGP sterilization process did not have a significant influence on M(n) or M(w) initially or through 12 weeks of in vitro conditioning when compared with EtO. Only indications of physical aging were evident in the analysis of the thermal and mechanical properties by differential scanning calorimeter and tensile testing for each sterilization processes. Using wide angle X-ray diffraction to determine morphology characteristics, it was determined that no changes were observed between the as molded, HPGP, and EtO specimens initially or through the 12 week in vitro conditioning period. Contact angle measurements revealed a significant reduction in the surface energy following treatment by the HPGP process, suggesting the formation of polar groups. However, surface chemistry analysis by ATR-FTIR indicated no significant chemical modification from either sterilization method. PLLA showed intermediate levels of residual hydrogen peroxide absorption following processing by HPGP.

Evaluation of the efficacy and usefulness of low temperature hydrogen peroxide gas plasma sterilization system for endoscopies

目的 探讨STERRAD(r)100S过氧化氢等离子低温灭菌系统在内窥镜消毒中的临床应用效果,并与福尔马林熏蒸灭菌法进行比较.方法 2005年1-3月,采用福尔马林熏蒸器械灭菌法完成92台手术104次熏蒸共2 706件内窥镜手术器械灭菌.2005年1-3月采用STER-RAD(r)100S过氧化氢等离子低温灭菌系统完成165台手术180个循环共4 950件内窥镜手术器械灭菌.对比两种方法的器械损耗率、手术感染率,并发放问卷调查医护人员对两种灭菌方法的满意度.结果 STERRAD(r)100S过氧化氢等离子低温灭菌系统在器械损耗率、手术感染率和医护人员满意度指标上均明显优于福尔马林熏蒸灭菌法(P＜0.05).结论 STERRAD(r)100S过氧化氢等离子低温灭菌系统具有环保、安全、低温、快速、节省费用和适用范围广的优点,具有极高的经济价值和社会价值。

Comparison of low-temperature hydrogen peroxide gas plasma sterilization for endoscopes using various Sterrad™ models

This study compared the effectiveness of sterilizing four types of endoscope using different models of the Sterrad system (Sterrad 50, 100, 100S and 200). Sterilization levels meeting international requirements were attained in all cases with carriers inoculated with Geobacillus stearothermophilus spores. The endoscopes were tested in half cycles ('overkill'). This is the first study to compare the Sterrad models marketed to date in terms of effective sterilization of endoscopes with narrow lumens.

Evaluation and quantification of reprocessing modification in single-use devices in interventional cardiology

The increasing demand in interventional cardiology urges for reprocessing of single-use-labelled medical devices. To fulfil this aim, accurate and validated regeneration protocols are mandatory to guarantee sterility, functionality and safeness. The reprocessing protocol was realized by decontamination with chloro-donors, cleaning with enzymatic solutions and hydrogen peroxide gas plasma sterilization. Reprocessing effects on ablation and electrophysiology catheters were evaluated by assessing physical–chemical changes on surfaces and bulks, as a function of the reprocessing cycles number. Conventional optical microscopy and environmental scanning electron microscopy (ESEM) underlined the presence of micro-scratches on the polyurethane shaft surface. A clear correlation was found between surface damages and number of reprocessing cycles. Atomic force microscopy (AFM) confirmed the occurrence of physical–chemical etching of the polyurethane shaft caused by the hydrogen peroxide plasma sterilization, with increasing of nano-roughness at increasing number of the reprocessing cycles. UV–Vis spectra performed on the incubation solution of polymeric shaft sample, showed an absorbance increase at about 208nm. This fact could be attributed to the water elution from the polymer of low molecular weight oligomers. The presence of hydrolysis products of the polymeric shaft after incubation demands both the characterization of the products released in the solution and the chemical characterization of the water exposed surface.